1. Technical Field
The present invention relates to a droplet ejecting apparatus.
2. Related Art
The droplet ejecting apparatus such as an ink jet printer forms an image by driving a recording head according to image data and ejecting ink droplets onto a recording medium from nozzles of the recording head.
In some recording head adopting full width array (FWA) technology in which plural nozzles are arranged on scanning lines throughout the entire width of the recording medium, for example, a cord wheel is attached on a rotation shaft of a drive roll for conveying the recording medium and a signal obtained by reading a mark on the cord wheel by an optical sensor is used for droplet ejection timing control.
The drive roll contains eccentric error due to manufacturing reason. The cord wheel also contains installation error and a print error of the mark thereon.
For the reason, cyclic mismatch is generated between an encoder signal for use in print clock and conveyance velocity of the recording medium so that the ejection timing deviates, thereby causing a deviation in a droplet shot position on a paper.